1. Field of the Invention
The present invention relates to a magnetic recording/reproducing device, and, more particularly, to a magnetic recording/reproducing device in which a mechanism body, including the chassis, is covered with a pair of top and bottom covers.
2. Description of the Related Art
In a magnetic recording/reproducing device for recording information onto or reproducing information from a magnetic disk incorporated in a disk cartridge, the mechanism body, formed into a unitary structure based on the chassis, is interposed between the top cover and bottom cover and integrally engaged therewith, whereby the mechanism body is covered by both the upper and bottom covers.
FIGS. 50 and 51 each illustrate a conventional example of such a magnetic recording/reproducing device. Referring to the figures, the top cover 100 has a flat top face 100a and a pair of side faces 100b that extend vertically downward from the side edges of the top face 100a. The side faces 100b are formed by bending portions of the top cover 100 vertically with respect to the top face 100a. Two leg portions 100c project downwardly from a lower end of one of the side faces 100b, with horizontally extending slits 100d formed in the leg portions 100c. In the same way, two leg portions 100c with slits 100d are formed at the lower end of the other side face 100b. The leg portions are formed on corresponding locations on the left and right side faces.
The bottom cover 101 has a flat bottom face 101a, and a pair of side faces 101b extending upright from both edges of the bottom face 101a. The side faces 101b are formed by bending portions of the bottom cover 101 vertically with respect to the bottom face 101a. Each of the side faces 101b has a pair of retainer portions 101c, which are formed in corresponding locations. The retainer portions 101c are formed by bending portions along horizontal lines of the side faces 101b inwardly and vertically with respect to the side faces 101b. Through holes 101d are formed in the retainer portions 101c.
The chassis 102 has a flat bottom face 102a, and a pair of side faces 102b extending upright from the side edges of the bottom face 102a. A screw receiving portion 102c is formed in an upper end of one of the side faces 102b. The mechanism body, including the loading mechanism and means for moving the head (not shown), is placed on the chassis 102. The mechanism body is formed into a unitary structure based on the chassis 102. A printed board (not shown) is fixed to the lower surface of the chassis 102, and has mounted thereon circuits for driving the mechanism body and a connector.
The top cover 100 and the bottom cover 101, and the chassis 102 are formed by punching out predetermined shapes from a metal blank sheet such as an iron plate, and bending the punched shapes.
In assembling the magnetic recording/reproducing device, the chassis 102 is placed on the retainer portions 101 of the bottom cover 101, and a screw 104 is inserted from the bottom face 101a side through each through hole 101d and screwed into the chassis 102, so as to fix the chassis 102 of the mechanism body within the bottom cover 101. Then, the top cover 100 is placed over the bottom cover 101 and moved horizontally in order to fit the retainer portions 101c into their corresponding slits 100d in the leg portions 100c, as a result of which the top cover 100 is retained by the bottom cover 101. A different screw 105 is then screwed from the outside of the top face 100a into a screw receiving portion 102c in order to fix the top cover 100 to the chassis 102. As a result, the top cover 100 and the bottom cover 101 are integrally engaged with each other via the chassis 102, so as to accommodate the mechanism body therein. In this case, a connector mounted onto the printed board is disposed inside an opening formed in a rear end where the upper and bottom covers 100 and 101 engage each other. In addition, the magnetic recording/reproducing device, while being incorporated in an external device of a computer body or the like, is electrically connected to the external device by inserting the external connector of the external device from the opening at the rear end where the covers engage each other, and connecting it to the connector on the printed board.
In the above-described conventional magnetic recording/reproducing device, however, the leg portions 100c of the top cover 100 are formed in corresponding positions on each side face 100b, so that when a plurality of top covers 100 are successively press-cut from the same metal blank sheet, the sides 100b of two adjacent top covers 100 must be separated by a distance greater than the total sum of the lengths of the leg portion 100c of one of the top cover 100 and its adjacent top cover 100, thus resulting in material wastage that prevents cost reduction.
In addition, since the top cover 100 is retained by the bottom cover 101 by fitting the retainer portion 100c into the slit 100d in the leg portion 100c in the direction of plate thickness of the retainer portion 101c, it becomes difficult to fit the retainer portion 101c into the slit 100d, unless the retainer portion 101c is accurately positioned with respect to its corresponding slit 100d along the vertical dimension. However, the height of the retainer portion 101c depends on the degree of its perpendicularity with respect to the side face of the bottom cover 101, so that unless the retainer portion 101c is made perpendicular to the side face, many processing difficulties result. Further, variations in the height of the retainer portions 101 occur easily, resulting in the problem that the chassis tilts when placed on the retainer portions 100c.
In addition, the bottom cover 101 and the chassis 102 are fixed to each other with a plurality of screws 104, and the top cover 100 and the chassis 102 are fixed to each other by a different screw 105, so that a larger number of screws must be screwed, which prevents cost reduction.
In the above-described conventional magnetic recording/reproducing device, the mechanism, formed into a unitary structure, and the printed board are covered by a pair of covers from above and below the mechanism and the printed board, resulting in the problems that the overall weight of the device and material costs cannot be reduced due to the use of two covers. In addition, upon integral engagement of both covers, the mounting position of the stepping motor, being the driving source for the mechanism for moving the head, is sometimes slightly adjusted. However, since the stepping motor is disposed inside an opening at the rear end where both covers engage each other, the adjustment is troublesome to carry out.
To overcome such problems, the front-to-back side dimension of the top cover is be made shorter than that of the bottom cover in order to expose the connector and the stepping motor through the top cover. In this case, the top cover does not have to cover the connector and the stepping motor, thus reducing material costs for the top cover by an amount corresponding to the reduced dimension, and allowing adjustment of the stepping motor to be performed more simply in a larger space. However, since the region around the connector is open space, there is no longer a positioning standard for inserting an external connector to the connector, so that it becomes troublesome to connect the external connector to the connector.